In GOA (Gate Drive On Array) technology, a gate driver is manufactured on a thin film transistor array substrate, via a manufacturing procedure of a thin film transistor (TFT) array, so as to achieve row-by-row scanning.
The GOA technology is widely applied and researched due to its benefit for the narrow frame design on a gate driving side of a display screen and reduction of cost.
With development of the oxide semiconductor thin film transistor (for example, IGZO, indium gallium zinc oxide thin film transistor), the corresponding integrated circuits surrounding the panel of the oxide semiconductor have become research focus. Since a carrier mobility ratio of the oxide semiconductor thin film transistor is 20-30 times that of an amorphous silicon thin film transistor, a charge-discharge rate of the thin film transistor on a pixel electrode can be greatly improved. It can be seen that, the oxide semiconductor thin film transistor can improve a response speed of a pixel and obtain a faster refresh rate so as to greatly improve a row scanning rate of the pixel and thus achieve an ultrahigh resolution in TFT-LCD. The GOA circuit of the oxide semiconductor thin film transistor may replace the GOA circuit of the amorphous silicon in the future.
However, in the prior art, the development of GOA circuit of the oxide semiconductor thin film transistor is few since there are many problems brought about by an electric property per se of the oxide semiconductor thin film transistor to be overcome. Specifically, IGZO belongs to an N type semiconductor and the hole number thereof is small. Hence, IGZO-TFT usually shows an excellent negative bias stress (NBTS) property. However, a positive bias stress property of IGZO-TFT is not good enough. The prolonged positive bias stress will result in forward drift of a threshold voltage (Vth) of TFT and thus a turning-on speed of IGZO-TFT device becomes slow, which seriously influences the GOA circuit.